In devices which receive and forward data, such as network packet switches for packet switched networks, the device can be configured to forward data with different latencies. For example, one device may be configured to forward data, such as a frame of data, with very low latency, such that forwarding of the data is initiated even while the frame is still being received.
Even though a low latency forwarding scheme provides extremely fast forwarding of data through a device, e.g., at line-rate speed, it has the drawback of not providing any error protection because the data begins to be transmitted before it is determined whether the frame contains a CRC (cyclic redundancy check) error, or is of legal length (e.g., at least 64 bytes).
To provide a much higher level of network error protection, a device may be configured to receive a complete frame of data before beginning the forwarding of the frame. This allows the device to perform CRC error checking and screen out frame fragments before forwarding. However, this increased network protection is achieved at the cost of higher latency.
Certain systems achieve an intermediate latency and limited network error protection by configuring the device to receive a threshold amount of data, but not necessarily a complete frame, before initiating a forwarding of the frame being received. This prevents fragments below a certain size from being forwarded, but may not provide CRC error checking.
There is an increasing need in current packet switched networks for network switches having multiple ports. These ports may have a variety of different end stations connected to the various ports. For example, one of the various ports at which data is received may be sending data (such as video data) which should be forwarded with a lower latency, and can tolerate less network error protection. Other ports may be sending data which should be forwarded with more network error protection, and therefore with a higher latency. However, configuring a multiport network switch into one of the earlier described modes does not accommodate the different types of traffic that the multiple ports of the device may carry to provide the proper network error protection and latency that is appropriate for the particular type of traffic.